I'm riding from the western burbs of Chicago to Minneapolis. From Prescott, WI, I need to get to the Diamond Lake Area. It looks like there are a bunch of pesky lakes and rivers to complicate things. Any advice would be appreciated.

It's got a few hills and make sure you leave Prescott with full bottles:

Cross river into MN on US 10. In a mile or two turn Right on Washington Cty #21 (St. Croix Trail) and go North several miles to a four way stop at Military Rd (Wash. Cty 20). Afton State Park on your Right has restrooms/water. Turn LEFT and go west on Military. Follow Military Rd until it joins with Baily Rd and continue West down the hill.

Option 1:

I'm unsure of the 494 crossing status and haven't done it. It's shorter and perhaps a better option. If you pursue this pick up the trail and cross using the north side of the north bridge over the Mississippi (Wakota bridge) and cross over the peninsula to the Mendota Bridge into south Minneapolis.

Option 2:
Follow the same trail North keeping the Mississippi River on your left as you proceed through DT St. Paul all the way to the Fort Road/Hwy 5 bridge crossing into Ft. Snelling (Use Ped crossing on north side accessed by stairs down. A track is there for your bike). Follow the trail north/west keeping the river on your right side (thru the parking lots) until you exit the trail in Minnehaha park. Turn left on 54th Street and go west around the south side of Lake Nokomis until the T with Pearl Park. Turn Left on the trail and then Right (West) to Diamond Lake.